Previous studies by this group to illuminate the mechanisms responsible for physiologic jaundice of the newborn rhesus monkey have shown that (1) bilirubin load presented to the newborn liver is 7 fold greater than in the adult; (2) during phase I of physiologic jaundice the conjugation of bilirubin is the rate-limiting step in transfer of bilirubin from blood into bile; and (3) relative deficiency of hepatic uptake of bilirubin appears responsible for phase II jaundice. Further study will include (1) carbon monoxide production during the first month of life to evaluate de novo synthesis of bilirubin; (2) the effect of biliary diversion in the newborn monkey to evaluate enterohepatic reabsorption; and (3) the role of various inducing agents on maturation of hepatic bilirubin transport and metabolism. Studies on the mechanisms of kernicterus have demonstrated the importance of free fatty acids in altering the physical state of bilirubin in the aqueous phase and its possible role in the transport of bilirubin into the central nervous system. These observations will be extended with laboratory and clinical studies of specific free fatty acids and their role in altering albumin binding of bilirubin and spectral and physical characteristics of bilirubin. BIBLIOGRAPHIC REFERENCES: Lee, K.S., Gartner, L.M. and Zarafu, I. Fluorescent Dye Method for Determination of the Bilirubin Binding Capacity of Serum Albumin. J. Pediatrics, Vol. 86, 2:280-285, Feb. 1975. Kandall, S., Saldana, L. and Gartner, L. Hemolytic Disease of the Newborn. Current Therapy (edited by Conn, H.F.) 27th Edition, 1975.